Retractable shelf



Jan. 5, 1960 D. F. PRESTON 7 2,919,966

RETRACTABLE SHELF Filed April 1, 1957 2 Sheets-Sheet 2 Ill re. 3.

i i I10 .Daw .Pessrwg 96 INVENTOR.

60 72 BY 14/5" 4rrafiws'z s 11/3205, I'd/Few, JZsrE/e lzgekrs.

RETRACTABLE SHELF Don F. Preston, Covina, Califi, assignor to AcmeApments being interengageable to lock the shelf in its extended positionin response to movement thereof into such position, and beingdisengageable to permit movement of the shelf into its retractedposition in response to .upward movement of the shelf beyond itsextended position.

pliance Manufacturing Company, Pasadena, Calif., a

corporation of California Application April 1, 1957, Serial No. 650,0406 Claims. Cl. 312-27 The present invention relates generally tomechanisms for moving such articles as shelves between retracted andextended positions and for locking them in their extended positions. Forconvenience, the invention will be considered hereinafter in connectionwith mechanisms or hardware for moving a retractable shelf upwardly andforwardly from a retracted position under a counter into an extendedposition forwardly of and at generally the same level as the counter,and for locking the shelf in such extended position, the. shelf carryinga mixer, or other appliance, or device. However, it will be understoodthat other applications of the invention are also possible.

Basically, the invention contemplates retractable shelf hardware whichcomprises a parallelogram linkage, including parallel, horizontalmounting and shelf brackets interconnected by two parallel arms eachpivotally connected at one end to the mounting bracket and at its otherend to the shelf bracket, the shelf bracket being movable upwardly andforwardly from a retracted position below and rearwardly of the mountingbracket into an extended position forwardly of the mounting bracket. Acounterbalance spring acting in tension is connected at one end to oneof the arms and is connected at the other end to the mounting bracket.The counterbalance spring counterbalances the weight carried by a shelfattached to the shelf bracket and means for adjusting the spring tensionto counterbalance various loads on the shelf is provided. Retractableshelf mechanisms of the foregoing general nature are well known.

-An important object of the present invention is to provide an improvedmeans for adjusting the counterbalance spring tension. Moreparticularly, an object of the invention is to provide adjustable meansconnecting one end of the counterbalance spring to the mounting bracketwhich includes a pin having an annular groove therein, means connectingthe spring to the pin, and two or more vertically spaced, keyhole shapedopenings in the mounting bracket each having an enlarged head portioninto which the pin as a whole is insertable and a smaller stem portioninto which the grooved section of the. pin is insertable, the stemportions of the openings extending downwardly and forwardly from thehead portions thereof toward the path of movementof the shelf bracketbetween the retracted and extended positions thereof. With thisconstruction, the pin may be inserted into the head portion of thekeyhole shaped opening which will provide the desired spring tension,whereupon the spring tension will pull the grooved section of the pininto the smaller stem portion of the opening to positively lock the pinin place, which is an important feature.

Another important object of the invention is to provide an improvedmeans for locking the shelf in its extended position. More particularly,an object is to provide a locking means which includes a rotatable,lobed locking element on one of the arms and a stationary lockingelement on the mounting bracket, these locking ele- Another object is toprovide the stationary lockingelement with first means engageable by oneof the lobes of the rotatable locking element to lock the shelf in itsextended position, and to provide the stationary locking element withsecond means engageable with another lobe of the rotatable lockingelement for rotating the rotatable locking'element to bring the firstlobe mentioned into engagement with the first means of the stationarylocking element in response to movement of the shelf into its extendedposition.

A further object is to provide the stationary locking element with thirdmeans engageable with the second lobe mentioned in response to movementof the shelf beyond its extended position for rotating. the rotatablelocking element to disengage the first mentioned lobe thereof from thefirst means of the stationary locking element, .whereby the shelf may bemoved through its extended position into its retracted position.

Another object is to provide a three-lobe rotatable locking elementwhich is generally triangular and any two lobes of which may function inthe manner hereinbefore outlined.

The foregoing objects, advantages, features and results of thepresentinvention, together with various other objects, advantages, features andresults thereof which will become apparent in the light of thisdisclosure may be attained with the exemplary embodiment of the inven-.tion described in detail hereinafter and illustrated in the accompanyingdrawings, in which:

Fig. 1 is a perspective view illustrating a typical installation of theinvention and showing a shelf carried by the invention in its retractedposition;

Fig. 2 is a perspective view similar to Fig. 1, but showing the shelf inits extended position;

Fig. 3 is an enlarged, fragmentary sectional view taken alon the arrowedline 33 of Fig.2;

Fig. 4 is an enlarged, fragmentary sectional view taken along thearrowed line 4-4 of Fig. 3; and I Figs. 5 to 11 aresemidiagrammaticviews illustrating successive relative positions oflocking elements constituting a locking means for locking a shelf in itsextended position.

i In the drawings, the numeral 20 designates a cabinet topped by acounter 22 and providing a compartment 24 having a front opening 26,which may be closed by a door, if desired. Movable into and out of thecompart ment 24 through the front opening 26 between a retractedposition below the counter 22 and an extended position forwardly of thecabinet 20 and at the same general level as the counter 22 is a shelf28. This shelf is supported by hardware units or mechanisms 30 and 32respectively mounted on opposite side walls of the compartment 24 belowthe counter 22. While the compartment 24 is shown as provided with sidewalls on which the hardware units 30 and 32 are mounted, it will beunderstood that these units may simply be mounted on the frame structureof the cabinet 20.

- The hardware units 30 and 32 are similar, differing only in that oneis a mirror image of the other, i.e., one is a left-hand unit and theother right-hand. Consequently, only the unit 30 will be consideredhereinafter,

it being understood that the description of the unit 30 is equallyapplicable to the unit 32.

Considering the mechanism 30, it comprises a pan: tograph orparallelogram linkage which includes parallel, horizontal, mounting andshelf brackets 34 and 36 inter-'- Patented Jan. 5, 1 960.v

connected by parallel arms 38 and 40, the arms 38 and 40 being connectedto the mounting bracket 34 at spaced points by pivots 42 and 4respectively, and being connected to the shelf bracket 36 at spacedpoints by pivots 46 and 48, respectively. As is characteristic of amechanism of this type, the shelf bracket 36 remains hori zontal at alltimes as it is swung from a retracted position below and rearwardly ofthe center of the mounting bracket 34 to an extended position forwardlyof the mounting bracket, as will be apparent from Figs. 1 and 2,respectively.

The mounting bracket comprises a plate 50 the major portion 52 of whichis offset inwardly relative to the compartment 24, the plate 50 alsoincluding portions 54, 56 and 58 which are offset outwardly relative tothe compartment 24- and which are seated against the corresponding sidewall of the compartment and secured thereto by screws, or the like. Theinwardly offset portion 52 of the plate 50 provides space behind theplate for heads, not shown, of the pivots 42 and 44. The outwardlyoffset portion 56 provides space therein for a locking means 60 to bedescribed while permitting the arms 38 and 40 to lie substantially fiatagainst the inwardly offset portion 52 of the plate 50. With thisconstruction, a relatively thin unit 30, occupying a minimum of space inthe compartment 24, results, which is an important feature. The plate 50is provided along its upper edge with a flange 62 which is secured tothe under side of the counter 22 by means of screws, or the like.

The shelf bracket 36 comprises a plate 64 to which the arms 38 and 40are connected by the pivots 46 and 48, and comprises a flange 66 towhich the shelf 28 is connected by means of screws, or the like. Theshelf 23 is provided with a handle 68 by means of which it may be movedbetween its extended and retracted positions The hardware unit 30 isprovided with a counterbalance spring 70 acting in tension between thearm 40 and the mounting bracket 34 to counterbalance the load carried bythe shelf 28, the spring tension being adjustable in a manner to bedescribed to counterbalance different weights on the shelf. The spring70 is connected at one end to an intermediate point on the arm 40 byengaging a hook 72 at such end of the spring with a pin 74 carried bythe arm 40, this pin having therein an annular groove 76 receiving thehook 72.

The other end of the spring 70 is adjustably connectible to the mountingbracket 34 at points spaced different distances from the path ofmovement of the shelf 28, i.e., different distances from the pivot 44,to vary the spring force applied to the parallelogram linkage. Theinwardly oifset portion 52 of the plate 50 is provided with a pluralityof vertically spaced, keyhole shaped openings 78 each having an enlargedhead portion 80 and a smaller stem portion 82, these stem portions allsloping downwardly and forwardly toward the path of movement of theshelf 23, i.e., toward the path of movement of the pin '74. A pin 84 isinsertable into each of the head portions 80 of the keyhole shapedopenings 78 and is provided therein with an annular groove 86, Fig. 4,forming a reduced diameter portion 88 receivable in each of the stemportions 82 of the keyhole shaped openings. The spring 70 is providedwith another hook 90 engageable with the pin 84 and receivable in anannular groove 92 therein.

As will be apparent, since the stem portions 82 of the keyhole shapedopenings 78 extend toward the path of movement of the pin 74, the springtension biases the pin 84 toward the extremity of the particular stemportion in which it is disposed, the inwardly offset portion 52 of theplate 50 adjacent each stem portion fitting snugly within the groove 86in the pin 84 so as to provide a rigi connection between the spring '70and the mounting bracket 34. However, the spring tension may be variedeasily by disengaging the hook from the pin 84, moving the pin toanother of the openings 78, and then reengaging the hook 90 with thispin. Thus, the spring tension may be adjusted to counterbalancedifferent loads on the shelf 28 very readily while still providing arigid anchor for the spring, due to the fact that the spring force actsto bias the reduced diameter portion 88 of the pin 84 into the closedend of the stem portion 82 in which it is disposed and due to the snugfit between the sides of the groove 36 in the pin and the inwardlyoffset portion 52 of the plate 50 adjacent such stem portion. It will benoted that since the openings 78 are formed in the inwardly offsetportion 52 of the plate 50, space behind the plate is provided for thatportion of the pin $4 which projects therethrough, which is anotheradvantage of the offset construction shown for the plate 50.

Considering the action of the counterbalancing spring 70 in more detail,when the shelf 28 is in its retracted position, the arms 33 and 40 slopedownwardly and rearwardly, the shelf bracket 36 being located below andrearwardly of the center of the mounting. bracket 34. Con: sequently, asthe shelf 28 is moved into its retracted position, the spring crossesthe axis of the pivot 44 so that, when the shelf is in its retractedposition, the spring acts to retain it in such position because of thisover: center action. Movement of the shelf 23 rearwardly be? yond itsretracted position is prevented by engagement of a stop 94 on the shelfbracket 36 with the arm 40.

When the shelf 23 is moved toward its extended posi: tion, the spring 70crosses the axis of the pivot 44 in the opposite direction and, as soonas it does, the spring acts to bias the shelf toward its extendedposition. The shelf 28 is locked in its extended position by the lockingmeans as, which will now be described.

The locking means 60 automatically locks the shelf 23 in its extendedposition as it is moved thereinto, and is releasable by moving the shelfupwardly slightly beyond its extended position. The locking means 60includes a stationary locking element 96 mounted on the outwardly offsetportion 56 of the mounting bracket plate 50 and disposed in the recessformed thereby, which further assists in reducing the over-all thicknessof the unit 30. The locking means 60 also includes a rotatable lockingelement 98 mounted on a pin 100 carried by the arm 40. This rotatablelocking element is generally triangular and is provided with three lobes102, 104, and 106. These lobes cooperate with various means on thestationary locking element 96 to lock the shelf 28 in its extendedposition and to release the shelf in response to movement thereofupwardly beyond its extended position, as will now be described.

Referring to Fig. 5 of the drawings, as the arm 40 is moved toward itsextended position, i.e., the position thereof corresponding to theextended position of the shelf 28, one of the lobes of the lockingelement 98, such as the lobe 104 thereof, moves upwardly past an end 108of a lower leg 110 of the locking element 96 as shown. If the lobe 104had not been in the position shown so as to clear the end 108 of the leg110, it would have struck the lower surface of the leg 110 to rotate thelocking element 98 into a position such as to permit one of the otherlobes to clear the end 108 of the leg 110. In either event, as upwardmovement of the arm 40 COD? tinues, the locking element 98 ultimatelyassumes a position corresponding to that shown in broken lines in Fig.5.

As the arm 40 reaches a position corresponding to the broken-lineposition of the locking element 98, the lobe 102 of the locking element98 engages the end 108of the leg 110 of the locking element 96 to rotatethe locking element 98 in the clockwise direction, if this is necessaryto cause the locking element 98 to assume the brgken line position ofFig. 5.

Referring now to Fig. 6, continued upward movement of the arm 40 causesthe lobe 104; to engage a lower sure nine;

face 112 of an upper leg 122 of the locking element 96, such, surfacesloping upwardly and forwardly in such a way as to rotate the lockingelement 98 in the counterclockwise direction to bring the lobe 104 intoengagement with a shoulder 114. When the lobe 104 is inserted into theangle between the surface 112 and the shoulder 114, upward movement ofthe arm 40 is terminated.

Such insertion of the lobe 104 into the angle between the surface 112and the shoulder 114 results in positioning the lobe 102 above an uppersurface 116 of the leg 110 of the locking element 96. Consequently, ifthe shelf 28 is now released so that the load thereon tends to move itdownwardly again, the lobe 102 engages the surface 116, as shown in Fig.7. A slight additional movement of the arm 40, as shown in Fig. 8,results in rotation of the locking element 98 to bring the lobe 102thereof into engagement with a shoulder 118, the lobe 102 being insertedinto the angle between the surface 116' and the shoulder 118. Theshoulder 118 is generally vertical and is located a distance from thepath of the pin 100 less than the length of the lobe 102 so that thelocking element 98 cannot rotate beyond the position shown in Fig. 8 topermit downward movement of the pin 100 and the arm 40. Consequently,the shelf 28 is now locked in its extended position. g.

Referring now to Fig. 9 of the drawings, in order to release the lockingmeans 60, the arm 40 is moved upwardly slightly above its extendedposition. At this juncture, the lobe 104 engages an end 120 of the upperleg 122 of thelocking element 96, on which the surface 112 and theshoulder 114 are formed. The lobe 104 is engageable with the end 120 ofthe leg 122 at this stage due to the fact that it was rotated clear ofthe shoulder 114 during the events illustrated in Figs. 7 and 8. The end120 of the leg 122 slopes upwardly and forwardly so that, as the arm 40is moved upwardly, the locking element 98'is rotated in thecounterclockwise direction, as shown in Fig. 10. The stop 94 engages thearm 38 to terminate the upward travel of the arm 40 with the element 98in a final position slightly short of that shown in Fig. 10 for thepurpose of relieving the elements 96 and 98 of unnecessary shock andwear.

If the shelf 28 is now lowered to move the arm 40 downwardly toward itsretracted position, as shown in Fig. 11, the lobe 102 is now alignedwith a surface 126 formed by the upper edge of the lower leg 110 of thelocking element 96. Engagement of the lobe 102 with the surface 126results in rotation of the locking element 98 in the counterclockwisedirection as the arm 40 continues to move downwardly, whereby the lobe102 clears the end 108 of the leg 110 to permit the locking element 98to move downwardly out of engagement with the locking element 96.Consequently, the shelf 28 is now free to move to its retractedposition. When the shelf 28 is returned to its extended position, theforegoing events are repeated.

Thus, the present invention provides a simple, effective means forlatching the shelf 28 in its extended position, while still permittingready release of the shelf for movement back to its retracted positionmerely by moving the shelf upwardly slightly above its normal extendedposition.

Although an exemplary embodiment of the invention has been disclosedherein for purposes of illustration, it will be understood that variousminor changes, modifications and substitutions may be incorporated insuch embodiment without departing from the spirit of the invention asdefined by the claims which follow:

1. Retractable hardware, including: a parallelogram linkage comprisingparallel mounting and movable brackets and two parallel arms eachpivotally connected at one end to said mounting bracket and at its otherend to said movable bracket, said movable bracket being movable from aretracted position into an extended position; a tension counterbalancespring; means connecting one end of said spring to one of said armsintermediate its ends;radjustable means connecting the other end of saidspring to said mounting bracket, said adjustable means including a pinhaving an annular groove therein, including means connecting said otherend of said spring to said pin, and including at least two keyholeshaped openings in said mounting bracket each having an enlarged headportion into which said pin as a whole is insertable and a smaller stemportion into which the grooved portion of said pin is insertable, saidopenings being located different distances from the path of movement ofsaid movable bracket between said retracted and extended positions andsaid stem portions of said openings being closer to said path than saidhead portions thereof; and means, including interengageable lockingelements on said mounting bracket and one of said arms, for locking saidmovable bracket in said extended position.

2. Retractable shelf hardware, including: a parallelogram linkagecomprising parallel, horizontal mounting and shelf brackets and twoparallel arms each pivotally connected at one end to, said mountingbracket and at its other end to said shelf bracket, said shelf bracketbeing movable upwardly and forwardly from a retracted position below andrearwardly of said mounting bracket into an extended position forwardlyof said mounting bracket; a tension counterbalance spring; meansconnectingone end of said spring to one of said arms intermediate itsends; adjustable means connecting the other end of said spring to saidmounting bracket, said adjustable means including a pin having anannular groove therein, including means connecting said other end ofsaid spring to said pin, and including at least two vertically spaced,keyhole shaped openings in said mounting bracket each having an enlargedhead portion into whichsaid pin as a whole is insertable and a smallerstem portion into which the grooved portion of said pin is insertable,said stem portions of said openings extending downwardly and forwardlyfrom said head portions thereof toward the path of movement of saidshelf bracket between said retracted and extended' positions; and means,including interengageable locking elements on said mounting bracket andone of said arms, for locking said shelf bracket in said extendedposition.

3. Retractable shelf hardware, including: a parallelogram linkagecomprising parallel, horizontal mounting and shelf brackets and twoparallel arms each pivotally connected at one end to said mountingbracket and at its other end to said shelf bracket, said shelf bracketbeing movable upwardly and forwardly from a retracted position below andrearwardly of said mounting bracket into an extended position forwardlyof said mounting bracket; a tension counterbalance spring; meansconnecting one end of said spring to one of said arms intermediate itsends; adjustable means connecting the other end of said spring to saidmounting bracket, said adjustable means including a pin having anannular groove therein, including means connecting said other end ofsaid spring to said pin, and including at least two vertically spaced,keyhole shaped openings in said mountingbracket each having an enlargedhead portion into which said pin as a whole is insertable and a smallerstem portion into which the grooved portion of said pin is insertable,said stem portions of said openings extending downwardly and forwardlyfrom said head portions thereof toward the path of movement of saidshelf bracket between said retracted and extended positions; and means,including interengageable locking elements on said mounting bracket andone of said arms, for locking said shelf bracket in said extendedposition, said locking means including means responsive to movement ofsaid shelf bracket upwardly beyond said extended position for releasingsaid locking elements from locking interengagernent.

4. Retractable shelf hardware, including: a parallelogram linkagecomprising parallel, horizontal mounting and shelf brackets and twoparallel arms each pivotally connected at one end to said mountingbracket and at its other end to said shelf bracket, said shelf bracketbeing movable upwardly and forwardly from a retracted position below andrearwardly of said mounting bracket into an extended position forwardlyof said mounting bracket; a tension counterbalance spring; meansconnecting one end of said spring to one of said arms intermediate itsends; means connecting the other end of said spring to said mountingbracket; and means, including a rotatable, lobed locking element on oneof said arms and a stationary locking element on said mounting bracket,for locking said shelf bracket in said extended position, said lobedlocking element including straight-sided triangular lobes, said lockingmeans including first means on said stationary locking elementengageable by one of the lobes of said rotatable locking element forlocking said shelf bracket in said extended position, said locking meansalso including second means on said stationary locking element andengageable by another of said lobes of said rotatable locking elementfor rotating said rotatable element to engage said one lobe with saidfirst means in response to movement of said shelf bracket into saidextended position, said locking means further including third means onsaid stationary locking element and engageable by said other lobe ofsaid rotatable locking element for rotating said rotatable lockingelement to disengage said one lobe from said first means in response tomovement of said shelf bracket beyond said extended position.

5. In combination: a stationary member; an arm pivotally connected tosaid stationary member and movable relative thereto between retractedand extended positions; a lobed, rotatable locking element carried bysaid arm and having triangular straight-sided lobes; a stationarylocking element carried by said stationary member; first means on saidstationary locking element engageable by one of the lobes of saidrotatable locking element to lock said arm in said extended position;second means on said stationary locking element and engageable byanother of the lobes of said rotatable locking element for rotating :e.or said rotatable locking element to engage said one lobe thereof withsaid first means in response to movement of said arm into said extendedposition; and third means on said stationary locking element andengageable by said other lobe of said rotatable locking element forrotating said rotatable locking element in response to movement of saidarm beyond said retracted position to disengage said one lobe from saidfirst means,

6. In combination: a parallelogram linkage comprising parallel mountingand moving brackets and two parallel arms each pivotally connected tosaid movable bracket at one end, said mounting bracket having a firstportion offset in one direction and the other ends of said arms beingpivotally connected to said first portion of said mounting bracket, saidmounting bracket having a second portion offset in the oppositedirection; and locking means including a locking element on one of saidarms and a locking element on said second offset portion of saidmounting bracket, for locking said movable bracket in a predeterminedposition relative to said mounting bracket. 7

References Cited in the file of this patent UNITED STATES PATENTS633,651 Kohn Sept. 26, 1899 693,127 Gardner Feb. 11, 1902 883,305 FetchMar. 31, 1908 1,137,261 Dyke Apr. 27, 1915 1,529,032 Meisner Mar. 10,1925 2,206,909 Lustig July 9, 1940 2,358,917 Emde Sept. 26, 19442,656,234 Koch Oct. 20, 1953 2,710,783 Chaft June 14, 1955 2,733,037Dunham a Jan. 31, 1956 2,802,711 Ulrich Aug. 13, 1957 2,822,229 CarlsonFeb. 4, 1958 FOREIGN PATENTS 159,220 Australia Oct. 7, 1956

